Lumen Of Rats Research Articles

Ileal mucosal growth during intraluminal infusion of ethylamine or putrescine.

Either ethylamine or the diamine putrescine was infused at the rate of 1 mumol/h for 66 h into the ileal lumen of rats. Total mucosal RNA, DNA, and protein content was greater in amine-treated rats than in rats receiving 0.9% NaCl. Growth was greatest in the mucosa surrounding the tip of the infusion catheter but was also observed 9 cm proximal and distal to the catheter tip. Infusion of these amines induced the activity of the enzymes ornithine and S-adenosylmethionine decarboxylase. Ornithine decarboxylase activity was increased 2- and 6-fold and S-adenosylmethionine decarboxylase activity 10- and 5-fold by putrescine and ethylamine, respectively. Induction of the polyamine biosynthetic enzymes was not accompanied by increases in the tissue content of polyamines. Putrescine, spermidine, and spermine content of the ileal mucosa surrounding the catheter tip was the same in 0.9% NaCl-, ethylamine-, and putrescine-treated animals. Finally, ethylamine was without effect on serum gastrin concentration in these experiments. The results suggest that amines regulate mucosal growth and may do so by modulating the activity of the enzymes involved in the synthesis of the polyamines.

Estrogen, progesterone, and the blood-uterine lumen permeability barrier in rats.

To investigate whether the existence of the permeability barrier between blood and the uterine lumen in rats is dependent upon hormone treatment, the effects of estradiol (E) and progesterone (P) on the abilities of [3H] sucrose, [14C] urea and tritiated water ([3H] OH) to enter the uterine lumen from blood were determined in immature, ovariectomized rats following i.v. injection of a radiolabeled test substance. To facilitate radioactivity recovery from the uterine lumen, intrauterine saline injections were administered to all animals except those treated continuously with E only. In one series of experiments, animals were treated for 3 days with or without E (0.5 μg/day) and P (2 mg/day) whereas, in another series, animals pretreated for 2 days with or without E (0.5 μg/day) were treated on the following day with or without P (2 mg). In both series, animals were killed 15 or 60 min after the i.v. injection. For [3H] sucrose, the uterine fluid (UF) radioactivity concentrations did not change significantly with time and were significantly lower than those of serum at 15 min postinjection in animals receiving any given hormone treatment. When [14C] urea was administered to animals treated continuously with E, the radioactivity concentrations either did not differ significantly between UF and serum or were significantly higher in UF. In animals receiving any other hormone treatment, UF radioactivity concentrations were significantly less than those of serum at 15 min postinjection, and whereas serum concentrations decreased with time, those of UF increased. By contrast, [3H] OH entered the uterine lumen readily, as indicated by radioactivity concentrations which were significantly higher in UF than in serum in all groups. The results of the present experiments suggest that a blood-uterine lumen permeability barrier to [3H] sucrose exists independently of E and P and that the existence of a barrier to [14C] urea is hormone dependent.

Somatostatin and gastrin release into the gastric lumen in rats.

Somatostatin and gastrin release into the gastric lumen was investigated in anaesthetized, vagally intact rats. The stomach was perfused at a flow rate of 0.5 mL.min-1. During perfusion with 0.1 M HCl or buffers of varying pH the somatostatin ans gastrin concentrations in the perfusate were less than 10 pg.mL -1 and approximately 30 pg.mL-1, respectively. Peptone caused a gastrin concentrations in the perfusate were less than 10 pg.mL-1 and approximately 30 pg.mL-1, respectively. Peptone caused a slight pH-independent increase in somatostatin release; gastrin release was unchanged despite an increase in serum gastrin from a basal of 15 +/- 4 to 155 +/- 34 pg.mL-1 during peptone stimulation. intravenous infusion of carbachol (1 microgram.kg-1.min-1) strongly stimulated luminal somatostatin and gastrin release (from 5 +/- 1 to 192 +/- 52 pg.mL-1 and from 27 +/- 5 to 198 +/- 41 pg.mL-1, respectively) during perfusion with 0.1 M HCl. Phosphate buffer perfusion at pH 7.5 abolished the cholinergic-mediated somatostatin release but the gastrin response was unaffected. It is suggested that changes of luminal hormone concentrations in the rat stomach do not reflect the secretory activity of the endocrine cells in the gastric mucosa.

Drug Absorption from In Situ Rat Small Intestine during Metoclopramide Administration

The effect of metoclopramide on the absorption of drugs in solution in the small intestinal lumen of rats in situ was studied. Metoclopramide in doses up to 50 mg/kg sc did not significantly modify the disappearance of isoniazid and quinidine from the small intestinal lumen. At the end of the absorption experiments, quinidine in the whole blood of the experimental animals was increased after metoclopramide. The blood level did not correlate to the drug disappearance from the intestinal lumen. The results probably differ from those obtained when drugs are given orally to subjects treated with metoclopramide.

Biochemical and Contraceptive Effects of an Intravas Device in the Rat

A study to determine whether a foreign body an intravas device (IVD) in the vasal lumen in rats would lead to any biochemical changes in the vas deferens that affect the fertilizing capacity of spermatozoa without affecting their morphology motility or transport is presented. On the side containing the IVD there were increases in protein sialic acid and phospholipids. Glycogen concentration and alkaline phosphates were significantly (p<.001) decreased. The fertilizing capacity of the vasal spermatozoa was unaffected.

Cytological Studies on the Cause of Pancreatic Secretion. II

It is suggested, from earlier studies on the functional changes of pancreatic cells, that the factor causing secretion of secretin from the mucous membrane of the duodenum when food is given orally, is “HCL+X”, and that this X must be a peculiar substance and may be effected by the quality of food. In order to prove the existence of this X, HCL (0.4%), protein (casein) and fat (sesame oil) were injected separately into the lumen of rat's duodenum, and the functional changes of the minute structure of pancreatic cells were observed.When HCL, casein and sesame oil are injected separately, pancreatic cells show but a slight discharge of granules, and the discharge pictures are similar in all three cases, the quality oh the substance having no special effect.When HCL is added to casein or sesame oil, a very strong discharge occurs soon after the injection and continues for 2 hours in the case of casein and 60 minutes in the case of sesame oil. The functional pictures are the same as. with oral administration of casein or sesame oil.Casein and artificfal gastric juice produce a slighter discharge than casein added with HCL, and moreover it only continues foi 60 minutes. It is believed that this is a result of the partial breakdown of casein by pepsin. When sesame oil and artificial gastric juice are injected, the picture. is quite similar to that of sesame oil and HCL.As shown by these results it is clear that the factor which causes secretion of secretin from the mucous membrane of the duodenum is not HCL, protein or fat alone, but a mixture of protein or fat with HCL. The fact that there is a difference in functional picture between “casein and HCL” and “sesame oil and HCL” is sufficient to show that X which differs with the substance exists in conjunction with HCL.On the other hand the production of zymogen granules (which are presumably the transformation of plastosomes) is in the case of duodenal injectin of the above-stateds ubstances too slight to be of question when compared to oral administration of them. All these facts show positively that the two functions of the pancreatic cells, i. e. discharging and producing of zymogen granules, are initiated by separate stimuli.

Cytological Studies on the Cause of Pancreatic Secretion

It is suggested, from earlier studies on the functional changes of pancreatic cells, that the factor causing secretion of secretin from the mucous membrane of the duodenum when food is given orally, is “HCL+X”, and that this X must be a peculiar substance and may be effected by the quality of food. In order to prove the existence of this X, HCL (0.4%), protein (casein) and fat (sesame oil) were injected separately into the lumen of rat's duodenum, and the functional changes of the minute structure of pancreatic cells were observed.When HCL, casein and sesame oil are injected separately, pancreatic cells show but a slight discharge of granules, and the discharge pictures are similar in all three cases, the quality oh the substance having no special effect.When HCL is added to casein or sesame oil, a very strong discharge occurs soon after the injection and continues for 2 hours in the case of casein and 60 minutes in the case of sesame oil. The functional pictures are the same as. with oral administration of casein or sesame oil.Casein and artificfal gastric juice produce a slighter discharge than casein added with HCL, and moreover it only continues foi 60 minutes. It is believed that this is a result of the partial breakdown of casein by pepsin. When sesame oil and artificial gastric juice are injected, the picture. is quite similar to that of sesame oil and HCL.As shown by these results it is clear that the factor which causes secretion of secretin from the mucous membrane of the duodenum is not HCL, protein or fat alone, but a mixture of protein or fat with HCL. The fact that there is a difference in functional picture between “casein and HCL” and “sesame oil and HCL” is sufficient to show that X which differs with the substance exists in conjunction with HCL.On the other hand the production of zymogen granules (which are presumably the transformation of plastosomes) is in the case of duodenal injectin of the above-stateds ubstances too slight to be of question when compared to oral administration of them. All these facts show positively that the two functions of the pancreatic cells, i. e. discharging and producing of zymogen granules, are initiated by separate stimuli.